If by "clean out" you mean repartition/reformat the drive to wipe it clean and then install XP Home, the answer is yes.
If you mean to try to delete all XP Pro files and then install Home, the answer is a qualified no. Since the operating system can't be deleted while it's running, you'll have to figure out a way to access the files on the drive without starting Windows. Since XP doesn't have true DOS, that most likely entails making the requisite 6 boot floppies, learning how to use them and try it from there. You'll have to be sure to get everything, including the registry. Since taking out the registry will also disable all the other software you have installed, you'll end up reinstalling all of it...so the end result is essentially the same as reformatting, only with less chance of success and a whole lot more work.
